1. Field of the Invention
The present invention relates to a motor drive device and a motor drive method of driving a motor for a vehicle electric pump.
2. Description of Related Art
Japanese Laid-open (Kokai) Patent Application Publication No. 2012-052640 discloses a vehicle including a mechanical oil pump, which is driven by an engine, and an electric oil pump, as oil pumps for supplying hydraulic pressure to an oil hydraulic circuit of a transmission, in which the electric oil pump is operated to supply hydraulic pressure during automatic stop of an engine.
Meanwhile, when a unit of controlling a motor of an electric pump receives an instruction value of a control amount for the motor from the outside through a communication line and controls the motor based on the received instruction value, noise may be mixed in the communication line.
When noise is mixed in a signal of the instruction value, motor may be driven by mistake, and if the motor is a synchronous motor, step-out may be caused.
As measures against such noise, delay processing for delaying change of a target value with respect to the instruction value may be performed. In this case, the raise of a fluid transfer amount and a fluid pressure may be delayed. For example, in a system configured to startup an electric oil pump associated with automatic stop of an engine, a decrease in hydraulic pressure may cause operation failure of a transmission.